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Date:	Mon, 3 Aug 2015 12:42:17 +0200
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Subject:	Re: [geda-user] Improved Find
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On Sun, Aug 02, 2015 at 07:22:56PM -0400, John Doty wrote:
> 
> On Aug 2, 2015, at 5:22 PM, Gabriel Paubert (paubert AT iram DOT es) [via geda-user AT delorie DOT com] <geda-user AT delorie DOT com> wrote:
> 
> > I always had the impression that the attribute handling rules are too 
> > complex;
> 
> Yes, although part of the problem is just confusing terminology. We could use the terms “override default” and “restore default” for promoting and deleting instance attributes. That would make the existing functionality clearer, I think.
> 
> > it would be much simpler to say that all attributes are promoted 
> 
> Ah, but that causes chaos for those of us who sometimes use “heavy” symbols.

At least for my workflow (I use gschem almost exclusively to design pcb), 
I have come to the conlusion that heavy symbols are a pain. I started from 
moderately heavy symbols and tend to go towards lighter and lighter symbols.

>You often want to be able to edit the symbol once to change attributes for all of its instances.

Couln't it be solved by better tools?

>About five years ago somebody changed the default attribute promotion rules to promote more things, and I still haven’t completely straightened out the resulting mess.

> 
> > and the symbol attributes are only sensible initial default values, which 
> > are always ignored when processing the schematics (generating a netlist 
> > being the most common example).
> 
> Promoting *nothing* unless you want to override it works better with heavy symbols.
> 
> > 
> > BTW, doesn't the net attribute have similar problems: many 74xx symbols
> > have net=VCC:14 (or 16, or 20) and net=GND:7 (or 8, or 10).
> 
> Yes, I forgot about that one.

And that's why I essentially never use it in my own symbols, with the
possible exception of ground pins for RF devices when they would make the
schematics too cluttered (or when the person doing the layout with
CadStar tells me that she needs one additional pin connected to ground
for each via in the central pad of a QFN with numbers starting from above 
the largest package pin number. These are completely virtual pin numbers, 
which I can't even use as a ground connection for a probe, so it's a
good thing that they don't even appear on the schematics).

    Gabriel

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